If t→ 0(∫₀¹ (3x + 5)^t dx)(1)/(t) = (α)/(5e)((8)/(5))(2)/(3), then α is equal to

Numerical Answer Type:
Enter a numerical value Answer: 64 to 64 +4 marks

Solution & Explanation

Related Formula

Standard indeterminacy layout resolution rules for limits matching form 1^∞:

t → 0 [g(t)](1)/(t) = e^ t → 0 (g(t) - 1)/(t)
Core Logic

Evaluate structural integration base at boundary limit initialization state t → 0:

∫₀¹ 1 dx = 1

This confirms it matches an indeterminate form of type 1^∞.

Step 1: Apply Taylor Series or L'Hopital's Theorem

Compute limits of logarithmic integration properties inside exponential power indices:

Exponent Expression = t → 0 ∫₀¹ (3x+5)^t dx - 1t

Applying L'Hopital's theorem to differentiate the numerator with respect to t yields:

∫₀¹ (3x+5)^t ln(3x+5) dx

Evaluating this at t = 0 gives:

∫₀¹ ln(3x+5) dx
Step 2: Complete the Final Form Match

Integrating via parts results in logarithmic value updates:

[ ((3x+5)ln(3x+5) - (3x+5))/(3) ]₀¹ = (8ln 8 - 5ln 5 - 3)/(3)

Passing components back through exponential foundations transforms terms to:

e(8ln 8 - 5ln 5 - 3)/(3) = ((8)/(5))(2)/(3) · ((64)/(5e))

Comparing with the target expression (α)/(5e)((8)/(5))(2)/(3) isolates the numerical solution directly: α = 64

Pattern Recognition

Treating 1^∞ structural transformations using logarithmic derivatives allows managing complex functions containing multiple integral boundaries effectively.

Chapter Mix

Class 11 Mathematics: Limits Class 12 Mathematics: Definite Integration

Reference Study Guides

More Limits Previous-Year Questions — Page 4

Q73 jee_main_2025_03_april_evening Evaluation of Limits
If x → 0 ( ( x)/(x) )(1)/(x²) = p, then 96 ₑ p is equal to
Numerical Answer. Answer: 32 to 32

Solution

Related Formula

For a limit of 1∞ form, where f(x) = 1 and g(x) = ∞:

[f(x)]g(x) = eg(x)(f(x) - 1)

Taylor expansion of x:

x = x + (x³)/(3) + (2x⁵)/(15) +
Core Logic

Here, x → 0 ( x)/(x) = 1 and x → 0 (1)/(x²) = ∞.

p = e^ x → 0 (1)/(x²)(( x)/(x) - 1) = e^ x → 0 ( x - x)/(x³)
Step 1: Finding limit exponent

Using expansion of x:

x → 0 ((x + (x³)/(3) + ) - x)/(x³) = x → 0 ((x³)/(3) + O(x⁵))/(x³) = (1)/(3)

Thus: p = e1/3

96 ₑ p = 96((1)/(3)) = 32
Pattern Recognition

Limits of forms like 1∞ always boil down to evaluating standard polynomials in the exponent. Using Taylor series expansion rather than L'Hopital's rule directly avoids taking multiple heavy derivatives.

Chapter Mix

Class 12 Mathematics: Limits, Continuity and Differentiability

Q jee_main_2025_07_april_morning Evaluation of Limits
x→ 0⁺ (5(x)(1)/(3)) ₑ(1 + 3x²)( ⁻¹3√(x))²(e^5(x)(4)/(3) - 1) is equal to
  • A. (1)/(15)
  • B. 1
  • C. (1)/(3)
  • D. (5)/(3)

Solution

Related Formula

Standard limits commands:

f(x)→ 0 ( (f(x)))/(f(x)) = 1 f(x)→ 0 (ln(1+f(x)))/(f(x)) = 1 f(x)→ 0 ⁻¹(f(x))f(x) = 1 f(x)→ 0 ef(x)-1f(x) = 1
Core Logic

We can rewrite the limit by grouping each term with its standard balancing factor:

x→ 0⁺ ( (5x1/3)5x1/3) · ( 3√(x) ⁻¹3√(x))² · ( ₑ(1 + 3x²)3x²) · ( 5x4/3e^5x4/3 - 1) × 5x1/3 · 3x²(3√(x))² · 5x4/3
Step 1: Simplify the Compensating Factor

Evaluate the remaining algebraic factor:

5x1/3 · 3x²9x · 5x4/3 = 15x7/345x7/3 = (15)/(45) = (1)/(3)

Since all individual standard limit terms approach 1, the value of the limit is exactly:

1 · 1² · 1 · 1 · (1)/(3) = (1)/(3)
Pattern Recognition

Shortcut: For standard limits involving (u), ln(1+u), ⁻¹(u), and e^u-1 as u → 0, replace each function directly with its argument:

(5x1/3)(3x²)(3√(x))²(5x4/3) = 15x7/345x7/3 = (1)/(3)
Chapter Mix

Class 11 Mathematics: Limits and Derivatives Class 12 Mathematics: Limits, Continuity and Differentiability

Q71 jee_main_2025_07_april_morning Points of Discontinuity
The number of points of discontinuity of the function f(x) = [(x²)/(2)] - [√(x)], x in [0,4] , where [·] denotes the greatest integer function is
Numerical Answer. Answer: 8 to 8

Solution

Related Formula

The greatest integer function [u] changes value and experiences a step discontinuity at any point where its inner argument u takes on an integer value.

Core Logic

Analyze the potential points where either component function argument changes into an integer within the interval x in [0, 4].

  • For [(x²)/(2)]:
  • (x²)/(2) can range from (0)/(2) = 0 up to (16)/(2) = 8. Integer values are reached at (x²)/(2) = 0, 1, 2, 3, 4, 5, 6, 7, 8, which means critical test locations are:

x = 0, √(2), 2, √(6), √(8), √(10), √(12), √(14), 4
  • For [√(x)]:
  • √(x) can range from √(0) = 0 to √(4) = 2. Integer values are reached at √(x) = 0, 1, 2, which means critical test locations are:

x = 0, 1, 4
Step 1: Audit Each Critical Point

Combine the set of test points within domain boundaries (0, 4):

x in 1, √(2), 2, √(6), √(8), √(10), √(12), √(14)

Let's evaluate the left and right hand limits at these specific values:

  • At x = 1: [√(x)] steps up while [(x²)/(2)] is constant Discontinuous.
  • At x = √(2): [(x²)/(2)] steps up while [√(x)] is constant Discontinuous.
  • At x = 2: Both functions experience an simultaneous integer step. Let's inspect:
  • f(2) = [2] - [√(2)] = 2 - 1 = 1
  • f(2^-) = [1.99] - [1.41] = 1 - 1 = 0
  • Since LHL ≠ value at point, it is Discontinuous. Continuing this verification down the full combined list confirms that none of the step jumps cancel each other out.

Step 2: Sum the Discontinuity Points

Counting all isolated inner points within (0, 4) yields exactly 8 locations:

Total Points = 8
Pattern Recognition

When two greatest integer functions drop steps simultaneously at the same point (like at x=2), always write out the explicit left and right limits manually, as simultaneous steps occasionally step in matching directions and maintain unexpected continuity.

Chapter Mix

Class 12 Mathematics: Limits, Continuity and Differentiability

Q70 jee_main_2025_08_april_evening Standard Limits and Expansion
Given below are two statements : Statement I : _ x arrow 0 ( ^ - 1 x + _ e 1 + x1 - x - 2 xx ^ 5) = (2)/(5) Statement II: x→ 1(x(2)/(1 - x)) = 1e² In the light of the above statements, choose the correct answer from the options given below:
  • A. Statement I is false but Statement II is true
  • B. Statement I is true but Statement II is false
  • C. Both Statement I and Statement II are false.
  • D. Both Statement I and Statement II are true.

Solution

Related Formula
(1+x) = x - (x²)/(2) + (x³)/(3) - x → a u^v = e(u-1)v
Core Logic

Verify Statement I via high-order Taylor polynomial series tracking, and determine Statement II values by resolving standard exponential limit properties.

Step 1: Expand Statement I Sequence Polynomials
⁻¹x = x - (x³)/(3) + (x⁵)/(5) - (1)/(2)[ln(1+x) - ln(1-x)] = x + (x³)/(3) + (x⁵)/(5) +

Summing terms together and subtracting 2x leaves:

x → 0 (2x⁵/5 + )/(x⁵) = (2)/(5) (Statement I is true)
Step 2: Verify Statement II Limit Power Structure

Evaluating the 1^∞ form configuration style:

e^ x → 1 ((2)/(1-x))(x-1) = e⁻² = (1)/(e²) (Statement II is true)
Step 3: State Conclusion

Both statements are correct.

Pattern Recognition

When a limit features a power factor of 5 in the denominator, you must track expansion variables through the 5th degree term to guarantee accuracy.

Chapter Mix

Class 11 Mathematics: Limits

Q55 jee_main_2025_29_jan_evening Differentiability of Modulus Functions
Let the function f(x) = (x² - 1)|x² - ax + 2| + |x| be not differentiable at the two points x = α = 2 and x = β. Then the distance of the point (α, β) from the line 12x + 5y + 10 = 0 is equal to:
  • A. 3
  • B. 4
  • C. 2
  • D. 5

Solution

Core Logic

The expression |x| is everywhere differentiable. Thus, non-differentiability relies completely on the modulus function containing the quadratic factor, i.e., |x² - ax + 2|.

Non-differentiability points generally happen where:

x² - ax + 2 = 0
Step 1: Evaluation of Roots

Given one of the roots is α = 2:

2² - a(2) + 2 = 0 6 - 2a = 0 a = 3

Substituting a=3 gives the other root β = 1. However, evaluating differentiability at x=1 reveals properties that invalidate standard options.

Step 2: Conclusion

Due to a technical contradiction in the configuration of the differentiable constraints at x=1, this question was officially dropped by NTA.

Pattern Recognition

If a quadratic inside a modulus has distinct real roots, it normally creates non-differentiable sharp turns unless a repeated multiplying factor outside cancels it out.

Chapter Mix

Class 12 Mathematics: Limits, Continuity and Differentiability

More Limits Questions — jee_main_2025_29_jan_evening

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